The Vaccine Trials and Epidemiology Branch (VTEB) of the Division of AIDS at NIAID supports prospective collaborative studies of HIV disease progression and transmission in populations with various risk factors for acquiring HIV. VTEB will be expanding its studies of HIV infection and disease in women and their children through two major initiatives: 1) the Women's Interagency HIV Study (WIHS) - will be conducted in close collaboration with a similar women's HIV natural history study (the HIV Epidemiology Research Study - HERS) initiated by the Centers for Disease Control and Prevention (CDCP). Awards for the WIHS will be made in July/August 1993. The main objective of the WIHS is to describe the spectrum of HIV-related disease in women. Investigators at various sites will follow 2500 HIV-positive women, and 775 HIV-negative high risk women at 6-month intervals to assess HIV-related outcomes; 2) the Women and Infants Transmission Study (WITS) II - is a refocused, recompetition of WITS I, which began in 1989. This study plans to enroll an additional 600-750 HIV-positive women (new recruits) and their infants (450-500) to those followed in WITS I; awards for the clinical sites will also be made in July/August 1993. The WITS II will study the effects of pregnancy on the course of HIV in women, identify factors which predict transmission from mother to fetus, and factors which influence disease progression in infants. Within the context of supporting the VTEB's cohort studies of HIV infection in women and children, this contract has 5 main objectives. These are to provide: 1. statistical and research design expertise for the WIHS and the WITS II, 2. statistical analyses and data management for the WIHS and WITS II, 3. central coordination of the systems for laboratory specimen processing, storage, and retrieval, 4. general statistical support for special projects of the VTEB, and 5. educational, clinical, and interviewer training activities involving statistical, data collection and management issues for these studies.